The Tough Touring 'Reverse Dome Nut Roof rack kit' Uses High Tensile Dome nut Bolts - reversed and housed in PLA Manufactured here in our workshop. When the kit is fitted - it provides a captive nut housing as well as spacer for Dual Cab roof rack installs where the vehicle has no factory rack mounts, and especially in newer Dual cabs where air bags in side cavities .
 
We use the 'Reverse Dome Nut Roof rack fitting kit hardware' as its a super strong way to fit the roof rack to the vehicle, while the round/curved edges of the dome nuts will not puncture deploying air bags in the event of a crash - (The Dome nuts head sits inside the cavity and the bolt thread end goes outwards through the hole, through the Spacer and captive bolt, then the rack foot is bolted to that on the outside. 
 
This kit is to be used to fit any roof rack to any vehicle after roof lining removal / inspection confirms that the vehicle manufacturer did not install factory roof rack mounts due to roof cavity having side protrusion air bags fitted... 
 
Obviously the Drilling of holes into air bags will cause their likely failure, as will insertion of any bolt shaft into the air bag cavity... So the Dome nuts are inserted 'Reversed' or ' Thread out' then rack feet bolted to their 'male' thread on the top of the roof.